We will test the hypothesis that reproductive toxicity in the male caused by PCBs involves direct effects on tests cells. SPECIFIC AIM A: To quantify cellular disruption of the testis epithelium du to PCBs. The hypothesis is that PCBs cause decreased numbers of germ cells. Particular sub-classes of male germ cells may be damaged. We will do light and electron microscopy of testes exposed in vivo to PCBs and will quantify damage using morphometry. Germ cells will be quantified using flow cytometry. Enzyme marker analysis will be used to confirm the effects on germ cells. SPECIFIC AIM B: To determine the direct effects of PCBs on Sertoli cells. The hypothesis is that PCBs decrease cell viability and interfere with cell functions. Sertoli cells will be prepared from animals having chronic exposure to PCBs. Cells from untreated animals will be exposed to PCBs in vitro. Cell viability will be assessed, including an analysis of apoptosis. Secretion will be monitored by measuring known markers. Membrane constituents involved in cell - cell interactions will be quantified. PCB effects on regulation by hormones will be determined. SPECIFIC AIM C: To determine the effects of PCB exposure on germ cells. The hypothesis is that PCBs act directly on germ cells. Experiments include viability analysis of cells exposed both in vivo and in vitro to PCBs. Apotosis will be examined. Flow cytometry will be employed. Enzyme markers unique to cell sub-types will be monitored as will surface molecules involved in germ cell- Sertoli cell adhesion. SPECIFIC AIM D: To determine the effects of PCB exposure on germ cell-Sertoli adhesion using bioassays. The hypothesis is that as a result of exposure to PCBs, Sertoli and germ cells are not able to maintain necessary somatic-germinal cell associations. Bioassays will quantify adhesion between Sertoli and germ cells. Sertoli-germ cell adhesion will be analyzed in an adherent cell assay with laser scanning cytometry. Bicameral Sertoli - germ cocultures will be used. SPECIFIC AIM E: To determine the effect of PCB exposure on specific intercellular junctions of the seminiferous epithelium. The hypothesis is that PCBs disrupt formation of intercellular junctions between Sertoli cells. Tight junctions and gap junctions will be examined. Junctions will be examined in vivo and in vitro. Light microscopy will include confocal analysis. Ultrastructural observations will include tracer studies and freeze-fracture. Western blots and ELISA methods will be used with antibodies specific for tight junctions and gap junctions. Analysis of gap junctions will also be done using laser cytometry and chop-loading.